dry wash vs streambed

dry wash and streambed both are nouns.

Word	Noun	Adjective	Verb	Adverb
dry wash	Yes	No	No	No
streambed	Yes	No	No	No

As nouns, streambed is a hypernym of dry wash; that is, streambed is a word with a broader meaning than dry wash:

dry wash: the dry bed of an intermittent stream (as at the bottom of a canyon)
streambed: a channel occupied (or formerly occupied) by a stream

Other hypernyms of dry wash include creek bed.

dry wash (noun)	streambed (noun)
the dry bed of an intermittent stream (as at the bottom of a canyon)	a channel occupied (or formerly occupied) by a stream